Doctor blade mechanism



April 1952 R. R. RICHARDSON EIAL 2,593,344

7 SheetsSheet 1 April 1952 R. R. RICHARDSON EI'AL 2,593,344

DOCTOR BLADE MECHANISM Original Filed Aug. 20, 1945 7 Sheets-Sheet 2ullllMllflllllllllllllwlllllh ,avt a/ agz" April 1952 R. R. RICHARDSONETAL 2,593,344

DOCTOR BLADE MECHANISM Original Filed Aug. 20, 1945 7 Sheets-Sheet 3 Q.EH41 Ap 1952 R. R. RICHARDSQN ET AL 2,593,344

DOCTOR BLADE MECHANISM Original Filed Aug. 20, 1945 7 Sheets-Sheet 4April 15, 1952 R. R. RICHARDSON ETAL 2,593,344

DOCTOR BLADE MECHANISM I Original Filed Aug. 20, 1945 7 Sheets-Sheet 5fagp/, R icardts'on dld lad [6mm Edmondis'on April 1952 R. R. RICHARDSONET AL 2,593,344

DOCTOR BLADE MECHANISM I tented Apr. 15, 1952 UNITED STATES PATENTOFFICE n 2,593,344 seems BLADE MECHAivIsM Ralph R. Richardson andWilliam H; Edmondson,

Chicago, Ill., assignors to United Biscuit Company, a corporation ofDelaware original application August 20, 1945, Serial No.

Divided and this application March 5, 1947; Serial No. 732,558

2 Claims.

This application is a division of our copendingapplication,fserialNo."611,533, which relates to printing "presses. a

This application relates to the construction of a doctor blade mechanismwhich regulates the amouritof ink carried by the 'printinglcylinder tothe work, and the'main objects of the invention are to provide doctorblade mechanism'which permits a wide range of adjustment of the doctorbladeto facilitate setting of the blade in advantageous operatingpositions relative to various'sizes of printing rolls which may beemployed inthe pressyand to provide an adjustable doctor blade structurewhich will afiord'a wide range of operating positions to suit variousoperating conditions whether or not Various printing roll sizes areinvolved. It is also an object of this invention to provide adjustabledoctor blade mechanism which may be quickly and easily adjusted togetherwith adjustingjmechanism which will provide micrometric adjustmentwithin a wide range of adjustment.

Other objects and advantages of the'invention will be'understood byreference to thefollowing specification and accompanying drawings (tensheets) wherein there is'illustrated an improved intaglio' printingpress embodying a selected form of the invention.

In the drawings? Fig. 1 is aside elevation, certain parts being brokenaway to more clearly illustrate other parts;

Fig.2 is an end "elevation looking "at the lefthand end of the press asshown in Fig. 1;

Fig. 3 is a planshowing the printing roll and doctor blade mechanism inthe main body of the press'frorn which there hasbeen removed forpurposes of illustration certain parts which normally overlie theprinting roll;

Fig. 10 is a section on the line [0-40 of Fig.

4: and

Figllll ,isa section onthelinel or FigLlO. The printing pressillustrated in the drawings embodies a printing roll I and an impressioncylinder 2, the paper or flat web 3 on which'jprinting is to be effectedbeingpassed between said printing roll and impression cylinder in the.direction indicated by the arrow 4. The impression roll 2 ispreferably. a rubber covered. roll and it is vertically slidablymountedthrough the agency of bearing blocks. S at itslopposite ends.inverti cally extending g'uideflmembersfie-fi which are supported by thestationary main frame .1. Downward movement of the impression roll 2maybe limited by engagement oiithfej'lowen edges of its bearing blocks 5with shouldersglie-liformed on a frame member 9 andthe impressioncylinder is normallyiurged downwardly bymea'nsllof an overlying roll.lll. The roll. Ill isvertically slidably mountedin the ways 5.6-6throughthe agency of its end bearing member's. II and suitable springmeans is provided for urging'the bearirlg blocks II and. the roll.lflfdownwardly to thereby urgethe r0112 downwardly. I j.

.The printing cylinder 1 is mounted for yertical adjustment toward and.from theimpression cylx printing cylinders ofasubstantiallrangeiofidiwameters in the press for cooperation withith'e same impression cylinder.The details of. "the printing roll mounting "and thesaid adjusting meansform' part of theisubject .matter' of our copending application,saidserial No. 611,533.

r 'The printing cylinder 1 is 'Tpreferably of the intaglio type and itjisjournalled in bearings such as indicated at I! .(Fig; 1) formedin avertically movable and adjustableauxillaryfiame member or'cradle. l3."Suitable bearin "caps"! are provided for cooperating with the bearingsl2 to'hold the en'd shafts l5 of the printing roll "in place in thebearings' I2.

The auxiliary frame memtenorcraule raeoz'iiprises opposite side portions'|'6 -l6, which 'are rigidly interconnected by transversely extendingframe elements such as indicatediat'. H. The side members [6-4 B areprovided with .vertibally extended bearing surfaces. such. as "indicatedat 18 cooperating with bearing surfaces 19 provided on the opposite sideportions 20-20 of the main frame 1 (see Figs. 1, 3 and 4).

The auxiliary frame structure I3 is vertically adjustably supported inthe main frame 1 by means of posts 2|-2|, there being two such posts ateach side of the auxiliary frame. The posts 2| have the auxiliary framel3 seated on their upper ends and secured thereto as indicated in Fig. 1and each of said posts 2| extends.

downwardly into a sleeve 22 (see Fig. 6) which is vertically slidablybut non-rotatably mounted within another sleeve 23. The outer sleeve 23is in turn rotatably mountedin a suitably bored out bracket or casting'24 which is fixedly mounted on an adjacent portion of the main frame 1.

The outer sleeve 23 is held against vertical movement in the casting 24by means of a pin 25 which is seated in the casting 24 and has its innerend projecting into a groove 26 provided in said outer sleeve. The upperend of the outer sleeve 23 is provided with a helical gear or worm wheel21 through which the outer sleeve may be rotated by means of acooperating helical gear or worm 28.

The inner sleeve 22 is keyed to the outer sleeve by means of keysindicated at 29-29 so that the inner sleeve is rotatable in unison withthe outer sleeve but is also vertically slidable relative to the outersleeve. Said inner sleeve is provided with internal screw threadingindicated at 39 cooperating with screw threading 3| provided on thelower portion of the post 2| so that when the sleeves 23 and 22 arerotated, the post 2| will be adjusted up or down. By rotating thesleeves 23 and 22, the vertical position of the post 2| and of theauxiliary frame |3 may be adjusted. This adjustment is made sufficientto permit the use of printing rolls of whatever range of sizes isdesired; for example, from 6- inch diameter rolls to 12-inch diameterrolls. The extent of adjustment required for that range of printingrolls is, of course, 3 inches plus whatever additional allowance may bedesired.

The printing roll may receive ink from any suitable means, such as anink trough or pan shown at 32 which is removably mounted in the cradlel3- The trough 32 may be removed with the cradle after ink inlet andoutlet conduits 33 and 34 respectively (Figs. 1 and 4) are disconnectedfrom the trough or pan. A doctor mechanism shown at 35 is arranged aswill hereinafter be explained so that it may easily and quickly I bemoved to anout-of-the-way position to permit the cradle l3 and printingroll I to be moved vertically into andout of place in the press.

For the purpose of adjusting the frame l3 up and down to accommodatedifferent sized rolls, it'is of course desirable that the four posts 2|be simultaneously adjusted. This is effected by simultaneously rotatingthe sleeves 22 around the respective posts. For that purpose there isprovided a shaft 52 suitably journalled in bearings 36 carried by themain frame I, the said shaft being equipped with worm-gears, such as theworm-gears 28 previously mentioned for meshing with the worm-wheels 21of the respectively adjacent post structures. By turning the shaft 52,the two adjacent post structures will be simultaneously adjusted up ordown in accordance with the direction in which the shaft 52 is rotated.To facilitate rotation of the shaft, one end thereof is provided with asquared projection 53 for receiving a suitable crank or hand wheel.

Extending parallel with the opposite ends of the apparatusthere areprovided shafts 54a and 541), each of which are suitably journalled inthe bearings 38 carried by the main frame 1. The shafts 54a and 54b aregeared to the shaft 52 so as to be rotated when the shaft 52 is rotated,suitable helical gearing comprising gears on the shaft 52 and gears 56on the shafts 54a and 54bbeing provided.

At the other ends of the shafts 54a and 54b there are provided helicalgears 51 which mesh with helical gears 58 provided on short shafts 59,which are suitably rotatably supported in bearings 39 carried by themain frame 1. shafts 59 carry worm-gears 28 in mesh with the worm-wheels2'! of the respectively adjacent post structures 2|. Rotation of theshaft 52 is thus imparted to the shafts 54a and 54b and to the two shortshafts 59 so that all four of the post units 2| will be simultaneouslyadjusted in the same direction. The various connecting gears are, ofcourse, properly selected to effect rotation of all of the gears 2'!simultaneously in' the same direction.

For the purpose of facilitating temporary separation of the printingroll and the impression cylinder, provision is made in the improvedstructure for easily and quickly lowering and raising the printing rollto a limited extent, for example, about -inch (or whatever distance maybe desired). In'this instance, the raising and lowering of the printingroll is effected by raising and lowering the auxiliary frame 3 on whichthe printing roll is supported. This is done by moving the inner sleeve22 (Fig. 6) and the post 2| at each corner, vertically. Such movement isaccomplished through the agency of a sleeve extension member 49 which isvertically slidable in the casting 24 and interconnected with the sleeve22 by means of a split collar 63 having internal flanges 64 and whichenter annular grooves 66 and 6'! respectively in the inner sleeve 22 andthe member 49. The parts of the split sleeve 63 are held in assembledrelation and in operative relation to the inner sleeve 22 and the member40 by means of a spring ring 4 I.

The lower end of the member 40 projects from the lower end of thecasting 24 and has pivoted to it a link 42 which extends downwardly andhas its lower end pivoted as shown at 43 (see Figs. 1 and 4) to an arm44 carried by a shaft 45. There are two shafts such as the shaft 45, oneat each end of the main frame, and there are of course two arms 44 oneach of the shafts for cooperating respectively with the post elevatingmechanisms at each corner. The shafts 45 are journalled in suitablebearings provided in the main frame 1. At one side of the apparatus thearms 44 are interconnected by a link 46 so that both shafts 45 will rockin unison (see Figs. 1, 2, and 4).

One of the shafts 45 (see Figs. 2 and 4) is provided at one end with anarm 4'! which extends at an angle to the adjacent arm 44 and has itsfree end connected by suitable pin and slot connection shown at 48 tothe outer end of a piston rod 49. The piston rod 49 carries a pistonhead 59 within an hydraulic cylinder 5| into which fiuid under pressuremay be delivered for moving the piston 59 in the required direction forrocking the arm 4! and the shafts 45. As shown in Fig. 4, the printingroll I is in a lowered position and out of contact with the web 3. Whenpressure fluid is admitted to the upper end of the cylinder 5|, it willof course force the piston 5|! downwardly therein to thereby-rock theshafts Said stash counterclockwise (Fig. 4) sothat the; assable manualor automatic means; and it will of course be understood that appropriatepiping is provided for delivering pressure fluid selectively to eitherend of the cylinder while releasing pressure fluid from the opposite endthereof.

Ink may be supplied to the ink trough or pan 32 in an uitable manner. Inthis instance, there is shown a motor-driven pumpfll (see Figs. 1 and 2)which draws ink from asuitable well or tankfil and discharges it intothe conduit 33 which discharges into the pan 32 (Fig. 1'). e t i Th inkis delivered to thelower portion of the pan 32 and the ink level may bedetermined by means of the position of the outlet opening through whichthe drain pipe 34 communicates with the ink pan. t he By reference toFig.4 it will be seen that the ink supplied to the roll I is carried bythe roll rearwardly and then upwardly to the printing line. Before theink-coated surface of the roll reaches the printing line. Surplus ink isremoved by, the doctoring mechanism; 35 previously re-- ferred to. Saiddoctoring mechanism 35 is of thexgeneral type shown in Edmondson Patent2,323,983 but modified and improved in some respects as will presentlybe described. y

Surplus ink may flow downwardly on the surface of the roll I and intothe pan 32 orany other suitable means may be provided for taking care ofthe ink which is doctored from the roll.

The doctoring mechanism 35 V is carried by a plate 19 which is, in turn,supported by a pair of arms 80-8ll. The upper ends of the arms 89 arescrewed or otherwise securely attached to the lower edge portions of theplate 19 and the lower ends of the arms are rotatably mounted on a shaft8|. The shaft 8| is supported by suitably bored out brackets 82-82 whichhave collar-like portions 83 secured to the upper ends of the innersleeves 22 of the adjacent vertically adjustable post structures (seeFigs. 4 and 6). The collar portions 83 may be of split form and suitablybolted together so as to permit assembly thereof around the upper end ofsaid sleeve 22 between upper and lower flanges 84 and 85 respectivelyformed integrally with the sleeve 22.

It will be seen that when the sleeve 22 is moved up or down by means ofthe toggle like elements consisting of the links 42 and the rock arms44, thearms 89, the plate 19, and the doctor blade mechanism will alsobe moved vertically in unison with the post structures and in unisonwith the printing roll. Hence, vertical adjustment of the printing rollby means of the hydraulically actuated toggle structure will occasion nochange in the relationship of the doctor blade to the printing roll. itshould be observed that the collar 83 is of such size that itlfitssnugly on the flanged upper end portion of the inner sleeve 22 so as tofirmly support the arms 80 and the doctor blade structure while at thesame time permitting the inner sleeve 22 to be rotated through theagency of the outer sleeve 23 for adjustment purposes already explained.

e For cooperatingwith the arms 80 to support the. plate 19 and thedoctor bl'ad' str' engage;

pos'iteend portions of the plate 19 are vertically l 6 slidably mountedon the adjacent portion of the main framestructure 1. For that purposeeach upper edge portion of the plate 19 near each end is provided with aslot 86 fitting slidably around and under a bolt 81, which is threaded;intothe,

adjacent main frame portion or into suitable brackets, such as indicatedat 88, which are in turn secured to the main frame proper; The

bolts 81 are preferably of a shoulder type as best" shown in Fig. 3,which will provide the required spacebetween the head of the bolt andtheada jacent surface of the supporting bracket or frame part to permitsliding of the plate as already indicated. The lower marginal'p'o rtionof the? plate at each end is also slidably secured to the main frame orto the brackets88; this being ac; complished in this instance by meansof clip plates'89; which are bolted as shown at 99 to the adjacent mainframe portion (seef Fieis. 1, 2 and 8). The frame part 1 is suitablyrecessed as indicated at 9| tq cooperate with the face of each clip 89to vertically slidably receive the lower marginal end portions ofthesaid plate i9.

The doctor blade structure proper comprisesfa' normally stationary shaft92 which maybe of square cross section for most of its length; but whichis provided with rounded end portions suitably journalled in bearings 93and 94 which are carried bythe platel9 (seeFigs'S and 10).

Abody casting 95 for the doctor blade is horizontallyslidably mounted onthe shaft 92, such mounting being effected at one end-through the agencyofan arm 96 which is bolted to'the end of the casting 95, as indicatedat 91 -91.- The arm 96 has a square opening broached out to properly fiton the square portion of the shaft" 92. At the other end of the bodycasting'95 (Fig. 10) the casting is slidably mounted'on' the shaftthrough the agency of a sleeve 98, a portion of which has a squaresocket fitting over an end' portion of the square shaft 92, and anotherportion suitably bored out to slidably and rotatably fit on a round orcylindrical portion 99 e of said shaft 92. The sleeve 98 fits insideasuit ably formed portion of the casting 95 and the sleeve is rigidlyconnected to the casting by suit-' able means, such as one or more setscrews such as indicated atlllll. Thus the sleeve 98 and casting aremovable horizontally as a single unit on the shaft 92.

To effect horizontal reciprocation of the body casting 95, there isprovided a tubular member lll'l which has a portion fittingtelescopically over an outer end portion of the sleeve 98. The tubularmember 18! is provided with a suitable roller I92 projecting inwardlyfrom its inner surface and projecting into a cam groove I93 pro vided inthe sleeve 98. The cam groove I93 is sio formed that rotation of thetubular member Hll in a fixed plane will effect reciprocation of thesleeve 98 and body casting 95. Additional details of the cam groove androller structure are shown in the aforementioned Edmondson Patent2,323,983.

bearing 93 or a washer I05 and a shoulder 196 formed on the shaft 92 bythe provision of a suitably reduced diameter portion ID! of the shaft.The tubular member IUI is further pre vided with spur gear teeth I88 bywhich the member may be rotated.

,Th doctor hla'de' I'99 ,is clamped between the- 7 being secured to ashaft III. The shaft III is journalled at its ends in end members I I2and I I3 (see Fig. 10) and near one end in a post member I I4. The postII4 has a suitably formed head as best shown in Fig. 4 including abolted-on cap portion for rotatably supporting the shaft Ill.

The shaft III, together with the doctor blade I09 and its carrying headIIO may be rocked to adjust the angular relationship of the doctor bladeto the printing roll. The means for effecting such rocking-of the shaftIII is best shown in Figs. 9 and 10. A there shown, the shaft III isprovided with a worm wheel I I5 which is keyed or otherwise secured tothe shaft. Said worm wheel I I5 meshes with a worm gear I I6 provided ona shaft I I1, which is rotatably mounted in the arm-like end member 96and provided at its lower end with a bevel gear I I6 which is keyed orotherwise secured to the shaft. The shaft II'I may be rotated by meansof a manually rotatable shaft II9 suitably journalled in the lower endportion of the arm 96 and provided with a bevel gear I20 which mesheswith the gear H8. The outer end of the shaft I I9 may be provided with ahand'lever or arm I2I to facilitate turning of said shaft I19.

The :end member H3 in which the shaft III ;is;j0.urnalled includes ashaft or post portion A 22 which is slidable inwardly and outwardly in asocket I23 provided in said end arm 96. The post portion I22 of the endmember H3 (see Figs. 9 and corresponds to the post portion II4 of theintermediate bearing support for the shaft III which is also slidableinwardly and outwardly in a suitable socket I24 provided in said bodycasting 95 .(see also Fig. 4). The end member II2 (Fig. 10) is similarlyslidable in a guideway I25 provided in the end of the body casting 95and it is adapted to be locked in selected position by means of aclamping screw I26. Each of the posts H4 and I22 are provided with gearteeth or racks I21 and I26 respectively which mesh with pinions, such asshown at I29 formed in a shaft I30, which is rotatably mounted in thebody casting 95 and end arm 96. By rotating the shaft I30, thesupporting members H4 and I22 for the shaft III may be moved inwardlyand outwardly, provided of course that the clamping screw I26 is soadjusted as to permit the end member II2 to follow the movement of theshaft III. For rotating the shaft I30 there is provided an adjustingmember I3I (see Fig. 11) which is suitably rotatably mounted in the bodycasting 95, secured against endwise movement and provided with worm-gearteeth or equivalent screw threading, such as shown at I32 in mesh withsuitable teeth I33 provided on a portion of the shaft I30. Because ofthe small pitch diameter of the gear I33 the adjusting member I3I isdisposed at a slight angle, as is clearly shown in Fig. 3 to properlydispose its teeth I32 in operative relationship to the teeth E33 whichare advantageously formed parallel with the axis of the shaft I30. Theouter end of the adjusting member I3I is preferably squared as indicatedto receive an adjusting wrench or lever to facilitate manual turningthereof. 7

When the shaft I II is adjusted up or down relative to the upper edge ofthe body casting 96, the gear II5 on the shaft III will roll over the"teeth of the worm gear II6 which is extended to maintain meshingrelationship with the gear II5 as best shown in Fig. 14. Hence, if theshaft III is adjusted upwardly from the s eam lowermost position shownin Fig. 9, the angle of the doctor blade I09 would be changed. The anglemay be restored to the initial angle by turning the shaft II9 as alreadyexplained.

The doctor blade structure is also rockable about the axis of the shaft92 to thereby adjust the doctor blade I09 toward and from the surface ofthe printing. roll. Such adjustment is particularly desirable tofacilitate the use of different sized printing rolls in the press.

For rocking the doctor blade structure about the axis of the shaft 92,said shaft is provided at one end with a worm-wheel I34 which is keyedor otherwise secured to the shaft. Said worm-wheel is in mesh with aworm-gear I35 carried by a shaft I36 which is suitably rotatably mountedin brackets I31 and I38 which are mounted on the plate 19. One end ofthe shaft I36 projects forwardly from the front bracket I31 and issuitably squared as shown in Fig. 13 to facilitate turning thereof bymeans of a wrench or the like. Turning of the shaft I36 and itsworm-gear I35 will, of course, effect turning of the shaft 92 and theentire doctor blade structure. Rotation of the shaft 92 is imparted tothe doctor blade structure by reason of the fact that the end arm 96 ismounted on a square portion of the shaft 92 as shown in Figs. 9 and 10.

The bearing I31 may be formed as a part of a housing I48 which ismounted on the plate 19 to cover a portion of the end arm 96 whichprojects outwardly through an opening I49 (Fig. 9) in the plate 19. Saidhousing I48 is suitably slotted as shown at I50 to permit the adjustingshaft II9 to project into readily accessible position.

The doctor blade structure may, in its entirety, be swung outwardly fromthe printing roll about the axis of the shaft 8I on which the structureis pivotally supported by means of the arms or brackets -80.

The means for driving the gear I08 and thereby effecting reciprocationof the doctor blade is such that said swinging movement of the doctorstructure may be readily effected without first removing ordisconnecting any of the driving connections. As shown in Figs. 2 and 3,the gear I08 is driven by means of a pinion I39 and a gear I40 which aresuitably mounted for rotation on the plate I9 or in suitable bearingbrackets secured thereto. The gear I40 is carried by a shaft I4I whichis provided at its other end with a helical gear I42 whichmeshes withanother helical gear l43. The gear I43 is carried by the upper end of ashaft I44 which is journalled in a bracket I45 carried by the side frameelement 20. The lower end of said shaft I44 may be connected directly toan electric motor I46 mounted on the side frame of the machine. Asuitable speed reducing gearing may be incorporated in the casing of themotor, if desired. The shaft I4I which carries the gears I 40 and I42 isjournalled in a suitable housing I4'I which is secured to the plate I9.

When the doctor blade structure is to be swung outwardly on the shaftiii, the upper locking bolts 8I--8'I and the clips 89-89 are removedwhereupon the doctor blade structure may be swung in its entirety to aninoperative, out-ofthe-way position. Such outward swinging movement ofthe doctor blade structure effects disengagement of the gear I42 fromthe gear I43 and when the structure is returned to operative positionthe gears I42 and I43 may be readily brought into mesh withoutdifficulty so that the driving connection between the motor I46 and thedoctor blade structure is restored.

The doctor blade mechanism is so' arranged that it follows the printingroll up and down into its inoperative and operative positionsrespectively, and said doctor blade mechanism is further readily movablein its entirety to an inoperative, out-of-the-way position facilitatingremoval of the printing cylinder and replacement thereof. The mountingof the doctor blade mechanism which permits the latter to be swung to anout-of-the-way position is such that its other adjustments are notnecessarily changed so that it may be readily restored to its normalrelationship to the printing roll without readjusting the setting of thevarious parts.

Various changes in the structure may be made while retaining theprinciples of the invention as referred to in the following claims.

We claim:

1. A doctor blade structure for a printing press 7 comprising a shaft, amain body longitudinally slidably mounted on said shaft, a doctor bladeholding head, a plurality of posts extending laterally from said headand slidably mounted in said main body to permit adjustment of therelationship of said head to said main body, said head including a shaftelement pivotally mounted in said posts for rotatably supporting saidhead, a gear secured to said shaft element and disposed within one ofsaid post members, a secand shaft rotatably supported by said main bodyextending transversely of said shaft element and provided with gearteeth meshing with said gear, means for adjusting said second shaft toeffect rotation of said gear and of said doctor blade shaft element, andmeans for effecting: longitudinal movement of said posts to adjust theposition of said head and its shaft element transversely of said mainbody, the arrangement being such;that said gear is permitted to"traverse said gear iteeth on said second shaft during said adjustmentof said posts, said second shaft remaining stationary.

2. A printing press having a printing roll and a doctor .-b-lade actingon said'printing roll to regulate the depth of ink carried by'said roll,a doctor blade carrying member, a doctor blade shaft rotatably mountingsaid doctor blade on a portion of said carrying member, a second shaftspaced. from said doctor blade shaft and pivotally, supporting saidcarrying member, said doctorblade being thereby mountedso as to beselectively adjustable about the axes of both of said shafts intoselected doctoring relation to said printing r011, means mounting saiddoctor blade shaft on said carrying member for adjustment toward andfrom said second: shaft, and means for effecting each of saidadjustments irrdependently of the other.

RALPH R. RICHARDSON. WILLIAM H. EDMO-NDSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date Re.21,2l2 Weiss Sept. 19, 19391,370,071 Tornberg Mar. 1, 1921 1,981,912 Fankboner Nov. 27, 19342,115,376 Weiss Apr. 26, 1938 2,323,983 Edmondson July 13, 1943 FOREIGNPATENTS Number Country Date 622,939 Germany Dec. 10, 1935

